1. Field of the Invention
The present invention relates to a plate-like object processing method for exposing a substrate such as silicon or the like by removing a laminate formed on a front surface of the substrate, the plate-like object including the substrate and the laminate.
2. Description of the Related Art
As is well known to those skilled in the art, a semiconductor device manufacturing process forms a semiconductor wafer in which a plurality of devices such as ICs, LSIs, or the like are formed in a matrix manner by a functional layer obtained by laminating an insulating film and a functional film on a front surface of a substrate such as silicon or the like. The devices in the thus formed semiconductor wafer are partitioned by division lines referred to as streets. The individual semiconductor devices are manufactured by dividing the devices from each other along the division lines.
Recently, in order to improve the throughput of a semiconductor chip such as an IC, an LSI, or the like, a semiconductor wafer has been put to practical use in which semiconductor devices are formed by a functional layer including a low dielectric constant insulator film (Low-k film) laminated on the front surface of a substrate such as silicon or the like, the low dielectric constant insulator film being formed of a film of an inorganic material such as SiOF, BSG (SiOB), or the like, or a film of an organic material as a polyimide-based polymer film, a parylene-based polymer film, or the like.
Division along the streets of such a semiconductor wafer is generally performed by a cutting device referred to as a dicing saw. This cutting device includes a chuck table holding the semiconductor wafer as a workpiece, cutting means for cutting the semiconductor wafer held on the chuck table, and moving means for moving the chuck table and the cutting means relative to each other. The cutting means includes a rotary spindle rotated at a high speed and a cutting blade mounted on the spindle. The cutting blade includes a disk-shaped base and an annular cutting edge mounted on the side surface of an outer circumferential portion of the base. The cutting edge is for example formed by fixing diamond abrasive grains having a grain size of about 3 μm by electroforming.
However, the above-described Low-k film is difficult to cut by the cutting blade. That is, the Low-k film is very fragile like mica. Therefore, when the semiconductor wafer is cut along the division lines by the cutting blade, the Low-k film peels off, and this peeling reaches the devices and causes a fatal damage to the devices.
In order to solve this problem, Japanese Patent Laid-Open No. 2005-142398 discloses a wafer dividing method including irradiating both sides in a width direction of a division line formed on a semiconductor wafer with a laser beam along the division line, thereby dividing a laminate along the division line by removal, and positioning a cutting blade between the outsides of the two laser processed grooves and moving the cutting blade and the semiconductor wafer relative to each other, thereby cutting the semiconductor wafer along the division line.